/*
 * Copyright (c) 2005 Voltaire Inc.  All rights reserved.
 * Copyright (c) 2002-2005, Network Appliance, Inc. All rights reserved.
 * Copyright (c) 1999-2005, Mellanox Technologies, Inc. All rights reserved.
 * Copyright (c) 2005 Intel Corporation.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/mutex.h>
#include <linux/inetdevice.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <net/arp.h>
#include <net/neighbour.h>
#include <net/route.h>
#include <net/netevent.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>
#include <rdma/ib_addr.h>
#include <rdma/ib.h>

MODULE_AUTHOR("Sean Hefty");
MODULE_DESCRIPTION("IB Address Translation");
MODULE_LICENSE("Dual BSD/GPL");

struct addr_req {
        struct list_head list;
        struct sockaddr_storage src_addr;
        struct sockaddr_storage dst_addr;
        struct rdma_dev_addr *addr;
        struct rdma_addr_client *client;
        void *context;
        void (*callback)(int status, struct sockaddr *src_addr,
                         struct rdma_dev_addr *addr, void *context);
        unsigned long timeout;
        int status;
};

static void process_req(struct work_struct *work);

static DEFINE_MUTEX(lock);
static LIST_HEAD(req_list);
static DECLARE_DELAYED_WORK(work, process_req);
static struct workqueue_struct *addr_wq;

int rdma_addr_size(struct sockaddr *addr)
{
        switch (addr->sa_family) {
        case AF_INET:
                return sizeof(struct sockaddr_in);
        case AF_INET6:
                return sizeof(struct sockaddr_in6);
        case AF_IB:
                return sizeof(struct sockaddr_ib);
        default:
                return 0;
        }
}
EXPORT_SYMBOL(rdma_addr_size);

void rdma_addr_register_client(struct rdma_addr_client *client)
{
        atomic_set(&client->refcount, 1);
        init_completion(&client->comp);
}
EXPORT_SYMBOL(rdma_addr_register_client);

static inline void put_client(struct rdma_addr_client *client)
{
        if (atomic_dec_and_test(&client->refcount))
                complete(&client->comp);
}

void rdma_addr_unregister_client(struct rdma_addr_client *client)
{
        put_client(client);
        wait_for_completion(&client->comp);
}
EXPORT_SYMBOL(rdma_addr_unregister_client);

int rdma_copy_addr(struct rdma_dev_addr *dev_addr, struct net_device *dev,
                     const unsigned char *dst_dev_addr)
{
        dev_addr->dev_type = dev->type;
        memcpy(dev_addr->src_dev_addr, dev->dev_addr, MAX_ADDR_LEN);
        memcpy(dev_addr->broadcast, dev->broadcast, MAX_ADDR_LEN);
        if (dst_dev_addr)
                memcpy(dev_addr->dst_dev_addr, dst_dev_addr, MAX_ADDR_LEN);
        dev_addr->bound_dev_if = dev->ifindex;
        return 0;
}
EXPORT_SYMBOL(rdma_copy_addr);

int rdma_translate_ip(struct sockaddr *addr, struct rdma_dev_addr *dev_addr)
{
        struct net_device *dev;
        int ret = -EADDRNOTAVAIL;

        if (dev_addr->bound_dev_if) {
                dev = dev_get_by_index(&init_net, dev_addr->bound_dev_if);
                if (!dev)
                        return -ENODEV;
                ret = rdma_copy_addr(dev_addr, dev, NULL);
                dev_put(dev);
                return ret;
        }

        switch (addr->sa_family) {
        case AF_INET:
                dev = ip_dev_find(&init_net,
                        ((struct sockaddr_in *) addr)->sin_addr.s_addr);

                if (!dev)
                        return ret;

                ret = rdma_copy_addr(dev_addr, dev, NULL);
                dev_put(dev);
                break;

#if IS_ENABLED(CONFIG_IPV6)
        case AF_INET6:
                rcu_read_lock();
                for_each_netdev_rcu(&init_net, dev) {
                        if (ipv6_chk_addr(&init_net,
                                          &((struct sockaddr_in6 *) addr)->sin6_addr,
                                          dev, 1)) {
                                ret = rdma_copy_addr(dev_addr, dev, NULL);
                                break;
                        }
                }
                rcu_read_unlock();
                break;
#endif
        }
        return ret;
}
EXPORT_SYMBOL(rdma_translate_ip);

static void set_timeout(unsigned long time)
{
        unsigned long delay;

        delay = time - jiffies;
        if ((long)delay <= 0)
                delay = 1;

        mod_delayed_work(addr_wq, &work, delay);
}

static void queue_req(struct addr_req *req)
{
        struct addr_req *temp_req;

        mutex_lock(&lock);
        list_for_each_entry_reverse(temp_req, &req_list, list) {
                if (time_after_eq(req->timeout, temp_req->timeout))
                        break;
        }

        list_add(&req->list, &temp_req->list);

        if (req_list.next == &req->list)
                set_timeout(req->timeout);
        mutex_unlock(&lock);
}

static int dst_fetch_ha(struct dst_entry *dst, struct rdma_dev_addr *dev_addr, void *daddr)
{
        struct neighbour *n;
        int ret;

        n = dst_neigh_lookup(dst, daddr);

        rcu_read_lock();
        if (!n || !(n->nud_state & NUD_VALID)) {
                if (n)
                        neigh_event_send(n, NULL);
                ret = -ENODATA;
        } else {
                ret = rdma_copy_addr(dev_addr, dst->dev, n->ha);
        }
        rcu_read_unlock();

        if (n)
                neigh_release(n);

        return ret;
}

static int addr4_resolve(struct sockaddr_in *src_in,
                         struct sockaddr_in *dst_in,
                         struct rdma_dev_addr *addr)
{
        __be32 src_ip = src_in->sin_addr.s_addr;
        __be32 dst_ip = dst_in->sin_addr.s_addr;
        struct rtable *rt;
        struct flowi4 fl4;
        int ret;

        memset(&fl4, 0, sizeof(fl4));
        fl4.daddr = dst_ip;
        fl4.saddr = src_ip;
        fl4.flowi4_oif = addr->bound_dev_if;
        rt = ip_route_output_key(&init_net, &fl4);
        if (IS_ERR(rt)) {
                ret = PTR_ERR(rt);
                goto out;
        }
        src_in->sin_family = AF_INET;
        src_in->sin_addr.s_addr = fl4.saddr;

        if (rt->dst.dev->flags & IFF_LOOPBACK) {
                ret = rdma_translate_ip((struct sockaddr *) dst_in, addr);
                if (!ret)
                        memcpy(addr->dst_dev_addr, addr->src_dev_addr, MAX_ADDR_LEN);
                goto put;
        }

        /* If the device does ARP internally, return 'done' */
        if (rt->dst.dev->flags & IFF_NOARP) {
                ret = rdma_copy_addr(addr, rt->dst.dev, NULL);
                goto put;
        }

        ret = dst_fetch_ha(&rt->dst, addr, &fl4.daddr);
put:
        ip_rt_put(rt);
out:
        return ret;
}

#if IS_ENABLED(CONFIG_IPV6)
static int addr6_resolve(struct sockaddr_in6 *src_in,
                         struct sockaddr_in6 *dst_in,
                         struct rdma_dev_addr *addr)
{
        struct flowi6 fl6;
        struct dst_entry *dst;
        int ret;

        memset(&fl6, 0, sizeof fl6);
        fl6.daddr = dst_in->sin6_addr;
        fl6.saddr = src_in->sin6_addr;
        fl6.flowi6_oif = addr->bound_dev_if;

        dst = ip6_route_output(&init_net, NULL, &fl6);
        if ((ret = dst->error))
                goto put;

        if (ipv6_addr_any(&fl6.saddr)) {
                ret = ipv6_dev_get_saddr(&init_net, ip6_dst_idev(dst)->dev,
                                         &fl6.daddr, 0, &fl6.saddr);
                if (ret)
                        goto put;

                src_in->sin6_family = AF_INET6;
                src_in->sin6_addr = fl6.saddr;
        }

        if (dst->dev->flags & IFF_LOOPBACK) {
                ret = rdma_translate_ip((struct sockaddr *) dst_in, addr);
                if (!ret)
                        memcpy(addr->dst_dev_addr, addr->src_dev_addr, MAX_ADDR_LEN);
                goto put;
        }

        /* If the device does ARP internally, return 'done' */
        if (dst->dev->flags & IFF_NOARP) {
                ret = rdma_copy_addr(addr, dst->dev, NULL);
                goto put;
        }

        ret = dst_fetch_ha(dst, addr, &fl6.daddr);
put:
        dst_release(dst);
        return ret;
}
#else
static int addr6_resolve(struct sockaddr_in6 *src_in,
                         struct sockaddr_in6 *dst_in,
                         struct rdma_dev_addr *addr)
{
        return -EADDRNOTAVAIL;
}
#endif

static int addr_resolve(struct sockaddr *src_in,
                        struct sockaddr *dst_in,
                        struct rdma_dev_addr *addr)
{
        if (src_in->sa_family == AF_INET) {
                return addr4_resolve((struct sockaddr_in *) src_in,
                        (struct sockaddr_in *) dst_in, addr);
        } else
                return addr6_resolve((struct sockaddr_in6 *) src_in,
                        (struct sockaddr_in6 *) dst_in, addr);
}

static void process_req(struct work_struct *work)
{
        struct addr_req *req, *temp_req;
        struct sockaddr *src_in, *dst_in;
        struct list_head done_list;

        INIT_LIST_HEAD(&done_list);

        mutex_lock(&lock);
        list_for_each_entry_safe(req, temp_req, &req_list, list) {
                if (req->status == -ENODATA) {
                        src_in = (struct sockaddr *) &req->src_addr;
                        dst_in = (struct sockaddr *) &req->dst_addr;
                        req->status = addr_resolve(src_in, dst_in, req->addr);
                        if (req->status && time_after_eq(jiffies, req->timeout))
                                req->status = -ETIMEDOUT;
                        else if (req->status == -ENODATA)
                                continue;
                }
                list_move_tail(&req->list, &done_list);
        }

        if (!list_empty(&req_list)) {
                req = list_entry(req_list.next, struct addr_req, list);
                set_timeout(req->timeout);
        }
        mutex_unlock(&lock);

        list_for_each_entry_safe(req, temp_req, &done_list, list) {
                list_del(&req->list);
                req->callback(req->status, (struct sockaddr *) &req->src_addr,
                        req->addr, req->context);
                put_client(req->client);
                kfree(req);
        }
}

int rdma_resolve_ip(struct rdma_addr_client *client,
                    struct sockaddr *src_addr, struct sockaddr *dst_addr,
                    struct rdma_dev_addr *addr, int timeout_ms,
                    void (*callback)(int status, struct sockaddr *src_addr,
                                     struct rdma_dev_addr *addr, void *context),
                    void *context)
{
        struct sockaddr *src_in, *dst_in;
        struct addr_req *req;
        int ret = 0;

        req = kzalloc(sizeof *req, GFP_KERNEL);
        if (!req)
                return -ENOMEM;

        src_in = (struct sockaddr *) &req->src_addr;
        dst_in = (struct sockaddr *) &req->dst_addr;

        if (src_addr) {
                if (src_addr->sa_family != dst_addr->sa_family) {
                        ret = -EINVAL;
                        goto err;
                }

                memcpy(src_in, src_addr, rdma_addr_size(src_addr));
        } else {
                src_in->sa_family = dst_addr->sa_family;
        }

        memcpy(dst_in, dst_addr, rdma_addr_size(dst_addr));
        req->addr = addr;
        req->callback = callback;
        req->context = context;
        req->client = client;
        atomic_inc(&client->refcount);

        req->status = addr_resolve(src_in, dst_in, addr);
        switch (req->status) {
        case 0:
                req->timeout = jiffies;
                queue_req(req);
                break;
        case -ENODATA:
                req->timeout = msecs_to_jiffies(timeout_ms) + jiffies;
                queue_req(req);
                break;
        default:
                ret = req->status;
                atomic_dec(&client->refcount);
                goto err;
        }
        return ret;
err:
        kfree(req);
        return ret;
}
EXPORT_SYMBOL(rdma_resolve_ip);

void rdma_addr_cancel(struct rdma_dev_addr *addr)
{
        struct addr_req *req, *temp_req;

        mutex_lock(&lock);
        list_for_each_entry_safe(req, temp_req, &req_list, list) {
                if (req->addr == addr) {
                        req->status = -ECANCELED;
                        req->timeout = jiffies;
                        list_move(&req->list, &req_list);
                        set_timeout(req->timeout);
                        break;
                }
        }
        mutex_unlock(&lock);
}
EXPORT_SYMBOL(rdma_addr_cancel);

static int netevent_callback(struct notifier_block *self, unsigned long event,
        void *ctx)
{
        if (event == NETEVENT_NEIGH_UPDATE) {
                struct neighbour *neigh = ctx;

                if (neigh->nud_state & NUD_VALID) {
                        set_timeout(jiffies);
                }
        }
        return 0;
}

static struct notifier_block nb = {
        .notifier_call = netevent_callback
};

static int __init addr_init(void)
{
        addr_wq = create_singlethread_workqueue("ib_addr");
        if (!addr_wq)
                return -ENOMEM;

        register_netevent_notifier(&nb);
        return 0;
}

static void __exit addr_cleanup(void)
{
        unregister_netevent_notifier(&nb);
        destroy_workqueue(addr_wq);
}

module_init(addr_init);
module_exit(addr_cleanup);